Sheet metal looseleaf binders, or holders, have been known for many years to attach catalogs, magazines and directories to specially designed protective covers that are not provided by the original publisher. Such covers and binders are frequently utilized for public or office telephone directories, magazines on airplanes and waiting rooms, and a myriad of other applications.
These metal binders include an elongated base strip with upturned ends, one of which serves as the pivotal connection for a blade-like binder and the other releasably holds the free end of the binder in position. The base as well as the blade are sheet metal stampings and while relatively inexpensive nevertheless require separate stamping operations and an assembly step to connect the blade to the upstanding end portions of the base strip.
One popular design has a slightly skewed slot in one end into which an "L" shaped leg on one end of the blade is inserted, and this defines the pivotal connection between the blade and the leg. This provides a very poor and sloppy pivotal connection that permits the blade when not attached to the other end of the base to flop around in almost any direction, and in fact easily fall out of the skewed slot.
The other upturned end of the base locks the free end of the blade in position, and it has a first entry slot skewed in a direction opposite the slot in the other end so that the blade must be twisted with a considerable degree of effort to slide it down into this entry slot. A locking slot is connected to the entry slot and after passing through the entry slot, the blade snaps into the locking slot.
In another design the blade is held into a closed locking slot with a key-ring type removable loop that passes through an aperture in the free end of the blade, preventing it from sliding out of the locking slot. This design, of course, requires three separate parts instead of the two in the first design described above.
A third metal binder design utilizes a wire-type blade with a spring-biased locking boss on its free end that must be pulled axially outwardly as the wire passes through an entry slot in one of the upstanding base ends, and then is released into a circular locking hole communicating with the entry slot. This design requires the manufacture and assembly of five separate parts, i.e. the base, the wire blade, the axially slidable boss, the spring for biasing the boss, and a fifth part--a washer that serves as spring seat for the biasing spring.
While all of these metal stamping binders are not expensive to manufacture, in large quantities a minor cost saving can be significant and if it were possible to reduce the manufacturing steps or assembly steps in these binders, it would provide significant savings.
All of these metal binders have no means to position the blade when the blade is not connected to the base at both ends, and this makes it more difficult for the installer of the cover to readily attach the magazine or directory in the binder. Another disadvantage is that the metal stampings have somewhat sharp edges, such as on the sides of the blades, the corners of the upstanding base ends and the edges of the entry slot, and create a risk of scratching or cutting the skin of the individual installing the directory into the cover, and also a risk to people reading the directories or catalogs.
It is a primary object of the present invention to ameliorate the problems noted above in metal cover binders.